I have been following this thread since it got made and even though I play at 1920x1080p (which means I have less chance of facing the issue as someone said above), I found some mods that cause problems even for me. Here is the testing process - I would always go at 5 am just out of Horseshoe outlook camp and check the train for passengers. Then I would increase the time to somewhere around 12 pm using Rampage and teleport to San Dennis and roam around for about sometime to check the spawning of passengers in trams and those passenger carts. I checked for multiple types of them that I won't be listing here. Then around 12.30 pm to 1pm, a train would pass through San Dennis, I would check it again for passengers. There is also a parked cargo train there. I would also check it. I sometimes found that some mod would cause the passenger train to appear with passengers but the parked cargo train to not appear. Then I would go out of San Dennis, towards South. There is a spot where about 4-5 Rosebill or something like that name of a bird appears and on an small island few Tricoloured and Blue coloured Herons appear. I would check for their presence and in their presence, I would check for the dip in numbers. Some mod caused one or two dip in numbers. I won't be listing them below. I am okay with it. I then went Northwards and checked for the presence of Whooping Cranes and Sandbill Cranes. I also checked North of Horseshoe Outlook multiple times to check the spawning of Wild Bay and Grullo Dun mustang. The tests were performed with Rampage, Snappy UI, Legal Screen Skip, Rainroad mod and Scripthook v2 and Online Content Unlocker installed. I checked it for all of the mods one by one or in a bunch of 4-5 mods installed.
I have a hunch that trains does not spawn with passengers during rainy and stormy weathers. Someone test this.
Here are the mods that caused disappearance in passengers or disappearance of passenger carts, trains or cargo train or of wildlife -
Improved Wildlife
Penetration
Realistic Gun Metals (Metals update)
Rowboat animations
Dismember everyone
Less Meat - Hunting
Automatic greet replies
Any horse Pre order mods caused problems for me. I tried about 3 of them, I guess 2 from nexus and one from this site.
Here are the mods that I have installed right now and I am playing with. NOTE - My stream and replace folder is empty.
These are the mods that did not cause issues to me or was too less to actually affect the gameplay.
Rampage
Legal Screen Skip
Scripthook v2
Online Content Unlocker
Snappy UI
Duels
Auto gold medals
So you lost your hat
Non Sticky hats
Performed armed executions in non combat stance
Disable Combat Stance
Optional Duel wield
Ingame world sounds only
Remove screen effects (both main file)
Collyrium Redone
No deadeye reload and glow
No auto ammo pickup
Just quit trolling already
Flo
Longer Horse Names
Corn sack fix
No auto horse holstering
realistic loot rebalance
less money
Banking
Realistic reload
Corpse spawn distance
Higher resolution content
Horse Loadout
Rifle Holster (thin one)
Improvements in Blood
LLRO
Just bleed already
PED accuracy fix
Horse Persistance
Kill Children
Quick Outfit customisation
Auto Challenges
Zen
Seats
Serenity
Smoking Complete
Bottoms Up
No stamina drain while running fix
Manual Pickup
Portable Dynamite Plunger
No Health Regen in Combat
Bounties Rebalance
Vegetation Tricks
No Time Slow wheel
Economy Rebalance by Maybelle
Ambient Gangs
Bandit Hideouts
I have everything working right now and the spawns including animal ones are good. After testing I added the experimental game config too to stay on the safe side. I also play tested the game for about 30 hours. I have deleted my save though and starting again afresh now without changing the mods ever again. I have got about 533 hours of gameplay but have not even played it lol.
Here are the mods that I don't have installed but while testing alone I did not find any issues. You can use these unless mentioned otherwise -
Bounty Hunting - Expanded and Enhanced ( I had turned all of the extra features off while testing)
No forced scope with no Spread and no sway by IMaverick
Shop Horses Unlocker
Just Shut up already
Serving Spoon fix
Timer message bugfix
No auto horse equip
Extra Difficulty settings
Buel Seam fix
Deputy fix
Irregular Lawman fix
NPC dualwield mod (The testing listed above was successful but I noticed that it does not do what it sets out to do. Without this mod, the men with dual holster appeared but while using this mod they did not appear for me. I was testing in Van Horn. I think it does not work well with Scripthook v2)
Unlock Bonus Cores
Injuries Overhaul
Immersive Faction Interaction tweaks
No out of Bounds Sniper (I tested the one by WesternandCo on Nexus)
Horse Shine Fix
LAW
Real Guns
Cowgirls Revisioned
Lost Treasures of New Austin
Happy Gamingg!!!
EDIT - I forgot to mention my graphics settings - Almost everything is set to Ultra for me. I also play at 1920x1080